There is more to the difference than just string tension. The shorter scale on an "identical" guitar means the bridge has been relocated or the neck has been shortened. Usually that means a difference in tone and in volume. Of course the difference usually is more than just "1/4". As the difference increases, the changes are more noticeable. There are many good reasons for different scale lengths. The final arbiter of whether it makes a difference is perception and preferences.

On a mandolin forum there are often questions from newbies regarding why mandolins are harder on the fingers than guitars. The answer frequently given is "greater string tension on the mandolin". However if you look at tension charters in general you'll find the opposite is true.

Somebody finally posted a diagram that showed the geometry involved. I can't reproduce it here but basically it showed two inverted triangles. The bases were the unfretted string; the hypotenuses are the fretted string - one from nut to fretboard and the other from bridge to fretboard. The remaining side, common to both triangles, is the distance from fretboard to unfretted string.

With a shorter scale length that third side is a greater proportion of the hypotenuses, that relationship translating to greater force.

How true all that is I don't know. Of course I'm sure that a mandolin having two strings fretted might be relevant too.

The curiosity was prompted after browsing a 'Vintage' (brand) website. It was noted that the 'parlour' guitar V880N had it's scale length quoted at 648mm whilst other (larger) models such as their 'dreadnoughts' and 'jumbo's' were 642mm. If I intended to buy, I would obviously try both (re 'here's an idea, try playing them' from guest on 24 Jan 01-49pm).

The main reason mandolins are harder on the fingers than guitars (if they are) is bad setup - but given the sizes involved you have to be a LOT more accurate setting up a mandolin. However, conversely, you can often get the action really low without rattling. Setting neck progression on mandolins is really hard as many have not got truss rods - something very rare nowadays on a guitar.